1. Field of the Invention
The present invention relates to a cleaning device, especially to such a cleaning device that uses chemicals to perform its cleaning operation.
2. Description of the Related Art
A cleaning device for cleaning semiconductor wafers is known as one of the cleaning devices which use chemicals to perform their cleaning operation.
In the semiconductor wafer cleaning device, a semiconductor wafer is transported by a transport device to cleaning process tubs, such as an ammonia peroxide process tub, a peroxidized hydrochloric acid process tub, a washing process tub, a hydrofluoric acid process tub, etc., that are provided in the cleaning device and then is subjected to various cleaning processes, such as an ammonia peroxide process, a peroxidized hydrochloric acid process, a washing process, a hydrofluoric acid process, and so forth. The cleaning processes are performed by bringing the semiconductor wafer into contact with the processing liquids within each of the cleaning process tubs.
The cleaning process tubs are placed within their respective cases, which allow the tubs to receive within them any semiconductor wafer but prohibit any process liquids from scattering out of the cases. The entrance portion of each case through which a wafer passes can open and close, but the entrance is normally closed in an airtight manner, so that the processing atmosphere within the case will be maintained constant.
However, since the entrance portion of each of the cases is constructed to open and close for allowing a wafer to pass through the entrance, a gap will be present at the entrance portion. Therefore, there is a problem that the interior of each case cannot be maintained to be in a complete airtight condition, but the atmosphere within the case may leak through the gap toward the outside of the case.
When the internal atmosphere of each case leaks out, the following problem will occur. When alkaline and/or acid toxic chemicals such as ammonia and hydrochloric acid are used to perform any cleaning operation, an ammonia gas and/or a hydrochloric acid gas may escape from the respective cases, and they may adversely affect any semiconductor wafer which is subjected to a cleaning process outside the cases, or may contaminate the surrounding environment resulting in corrosion in any equipments, such as transport devices, etc., that are arranged in the cleaning device.